My first amp build. Cap smoked after a few minutes.

[louderock]

Just built my first amp. It's a 5f4 Tweed Super kit from Weber. I just finished the wiring this morning and did a slow power-up with a bulb current limiter and my variac. Started with no tubes, then added the rectifier, then the preamp tubes, then the power... All seems well with that.

Plugged in a guitar and played for about 20 seconds and then the smoke started so I flipped the power switch. The second cap from the power side ( 16mf @450 ) was smoking and oozing from the negative/ ground side. The polarity is correct so I'm wondering if this is just a bad cap or did something else cause this problem? Any thoughts? I did not measure any voltages on the tubes/ board prior to this happening.

[WaltC]

could be a bad electrolytic cap. replace it and remove the power tubes. fire it up and measure the voltages on the rectifier, power tube sockets, and preamp sockets and post 'em and let's take a look.

[torquil]

Wow, too bad. What an anticlimax... Try to contact Weber, they can probably help you.

Torquil

[louderock]

Originally Posted by torquil

Wow, too bad. What an anticlimax... Try to contact Weber, they can probably help you.

Torquil

Tell me about it. I'm all excited... It works! It works! fffftttttphttt......Bummer!

I'll have to pick one up tomorrow. These are the Weber caps. Maybe I should just pop in some Spragues.

[zzmoore]

I am sure, by now, you are aware of the bad batch of caps that Weber got. You may have a much smaller value than you realize....
Good Luck

[Jerry Glass]

The first thing that struck me is that you state that the cap is oozing from the negative end. The negative end should be solid; the positive end should have an insulator. I would venture to say that the cap has its sleeve reversed and is actually in backwards.

[louderock]

I'm just getting some info on the fake cap scam. Could be the issue here. These caps have the groove on both ends which seems weird. Time to order some quality caps!!

[efnikbug]

Cut the cap open and show us what's inside!

[grabs popcorn]

[Big Dan]

Wow, if this is true, shouldn't Weber ship you a set of caps free?

[SamBooka]

I think weber are in Damage Control. They said they need X thousand caps for stock and to replace the funky ELONs. Their supplier said "no problem.. uh.. cept we can only send you X hundred"

I have about 20 unused ELON I need replaced. I am not in a hurry so let them deal with the angry customers first. Once the smoke clears (litterally?) I will do a big order and get the caps repaced at the same time.

[louderock]

Houston, we have a problem.

[schmidlin]

Yep, what's the inside value say?

[louderock]

Originally Posted by schmidlin

Yep, what's the inside value say?

It doesn't have anything written on it. Only the polarity marking.

[gldtp99]

I'd get on the list for replacement/refund (refund preferred in this case) for the three 16uF/450V caps and the 100uF/150V bias cap.
If this was my amp, i'd order F&T axial caps: 16uF/475V (x3) and one 100uF/100V.
I'd install these quality caps and enjoy my new amp---- again, if this was on my bench, i'd use a real 5U4GB rectifier tube as i have a good supply of NOS GE, RCA sitting here----the F&T axial caps are smaller in physical size than the Sprauge Atoms and i believe would fit the space provided better than the Atoms---i've had good service from Sprauge Atoms, F&T's, and Xicon axial caps for years.
It's really a shame that Weber got screwed with these "counterfit e-caps"---- they are a stand-up company and didn't do anything to deserve the problems they're going through with this-----i hope they get the e-cap problem straightened out soon.
The F&T's are available from many vendors--- in my AES catalog the 16/475's are $4.95/ea and the 100/100 bias cap is $1.95.
The Xicon 22uF/450V is $2.10 and the 100uF/100V bias cap is 91 cents from Mouser.
These are just examples--- there are many other great vendors for these caps, i just have the Mouser and AES catalogs sitting right here...............gldtp99

[pbradt]

Originally Posted by louderock

Tell me about it. I'm all excited... It works! It works! fffftttttphttt......Bummer!

I'll have to pick one up tomorrow. These are the Weber caps. Maybe I should just pop in some Spragues.

F&T Caps are just as good, less money and take up less room on the board.

I would never build a Weber kit, but if I did, in addition the the jacks, pots, switches, pilot lamp and fuse holder, I'd definitely upgrade ALL the caps. Especially the electrolytics.